This invention relates to the polymerization of olefins. In another aspect, this invention relates to the polymerization of 1-olefins in the presence of a chromium oxide catalyst and an adjuvant. In another aspect, this invention relates to a method of polymerizing 1-olefins in the presence of a catalyst such as chromium oxide and an aromatic compound such as benzene, o-xylene, monohalogenated derivatives of benzene and o-xylene and mixtures thereof. In yet another aspect, this invention relates to the polymerization of 1-olefins in the presence of a supported chromium oxide catalyst that has been pretreated with an aromatic compound such as benzene, o-xylene, a monohalogenated derivative of benzene or o-xylene or mixtures thereof.
High melt index is an important characteristic in a polymer. Since melt index is indicative of molecular weight and thus is further a measure of flow of the polymer, the higher the melt index of the polymer the better the polymer will perform for purposes where complete polymer flow to fill a mold, or the like, is required for the formation of an article prior to experiencing any setting of the polymer. A method to obtain polymers having a high melt index, therefore, is of significant value to the art.
It has now been discovered in accordance with this invention that the use of an adjuvant, which consists essentially of at least one aromatic compound selected from among benzene, o-xylene, and monohalogenated derivatives thereof, results in the production of a polymer having a higher melt index relative to polymers made under similar conditions in the absence of the adjuvant.
It is an object of the present invention, therefore, to provide an improved method for producing polymers and copolymers of 1-olefins.
Another object of the present invention is to provide a method for producing polymers and copolymers of 1-olefins having an increased melt index.
Other aspects, objects, and the several advantages of this invention will be apparent from the disclosure and the appended claims.